Correspondence among sevelamer- versus calcium-treated patients. The lower than expected overall all-cause mortality rate after 12 months of study prompted an 8-month extension of the recruitment phase, and a total of 466 instead of 360 individuals was recruited. Although the magnitude of the observed effect was unexpectedly large and possibly amplified by uncontrolled factors, the positive finding for both all-cause mortality and a more restricted end point such as cardiovascular mortality due to cardiac arrhythmias suggests that the sample size (hence the study power) should not be regarded as an issue, as highlighted by the reader.

However, contrary to the findings by Vaux et al,1 we2 previously noted a significantly increased risk of infection with buttonhole cannulation with 12 AVF infections (9 exit site and 3 Staphylococcus aureus bacteremia) in buttonhole cannulation versus none with standard cannulation (P 5 0.003). The skin disinfection protocols were similar in the 2 studies and neither used topical antibiotic prophylaxis. It is likely that it takes time for buttonhole infections to materialize, often beyond the first year of study.3 Thus, despite the lack of buttonhole infections seen by Vaux et al,1 we believe that buttonhole cannulation carries an increased risk of infectious complications.4 Jennifer M. MacRae, MSc, MD Sofia B. Ahmed, MSc, MD Brenda R. Hemmelgarn, MD, PhD University of Calgary Calgary, Canada

Biagio Di Iorio, MD PO “A Landolfi,” Solofra (AV), Italy

Acknowledgements This Reply is written on behalf of the INDEPENDENT Study authors Donald Molony, Cynthia Bell, Vincenzo Bellizzi, Domenico Russo, and Antonio Bellasi. Financial Disclosure: The INDEPENDENT Study authors, including Dr Di Iorio, have declared relevant financial interests (details available in7).

References 1. Obi Y, Hamano T. The change history of the INDEPENDENT Study in the ClinicalTrials.gov database. Am J Kidney Dis. 2014;63: 164. 2. Di Iorio BR, Cucciniello E, Bellizzi V. Vascular calcification and QT interval in incident hemodialysis patients. J Nephrol. 2009;22:694-698. 3. Di Iorio BR, Bortone S, Piscopo C, et al. Cardiac vascular calcification and QT interval in ESRD patients: is there a link? Blood Purif. 2006;24:451-459. 4. Chertow GM, Burke SK, Raggi P. Sevelamer attenuates the progression of coronary and aortic calcification in hemodialysis patients. Kidney Int. 2002;62:245-252. 5. Block GA, Spiegel DM, Ehrlich J, et al. Effects of sevelamer and calcium on coronary artery calcification in patients new to hemodialysis. Kidney Int. 2005;68:1815-1824. 6. Block GA, Raggi P, Bellasi A, Kooienga L, Spiegel DM. Mortality effect of coronary calcification and phosphate binder choice in incident hemodialysis patients. Kidney Int. 2007;71:438-441. 7. Di Iorio B, Molony D, Bell C, et al. Sevelamer versus calcium carbonate in incident hemodialysis patients: results of an open-label 24-month randomized clinical trial. Am J Kidney Dis. 2013;62(4):771-778. Originally published online October 28, 2013. Ó 2013 by the National Kidney Foundation, Inc. http://dx.doi.org/10.1053/j.ajkd.2013.09.005

Buttonhole Cannulation Technique as the Cannulation Method of Choice To the Editor: We read with great interest the randomized trial by Vaux et al1 that demonstrated improved arteriovenous fistula (AVF) survival with buttonhole compared to standard rope ladder cannulation in conventional hemodialysis patients. Use of a polycarbonate peg to create buttonhole tracks may result in less multiple-track formation. It is possible that eliminating the multiple tracks reduces the difficulty of needling and thus both reduces the requests for radiologic intervention and perhaps lessens stenosis formation, ultimately resulting in improved AVF survival. Am J Kidney Dis. 2014;63(1):164-173

Acknowledgements Financial Disclosure: The authors declare that they have no relevant financial interests.

References 1. Vaux E, King J, Lloyd S, et al. Effect of buttonhole cannulation with a polycarbonate peg on in-center hemodialysis fistula outcomes: a randomized controlled trial. Am J Kidney Dis. 2013;62(1):81-88. 2. MacRae JM, Ahmed SB, Atkar R, Hemmelgarn BR. A randomized trial comparing buttonhole with rope ladder needling in conventional hemodialysis patients. Clin J Am Soc Nephrol. 2012;7(10):1632-1638. 3. Van Eps CL, Jones M, Ng T, et al. The impact of extendedhours home hemodialysis and buttonhole cannulation technique on hospitalization rates for septic events related to dialysis access. Hemodial Int. 2010;14(4):451-463. 4. Nesrallah GE, Mustafa RA, Macrae J, et al. Canadian Society of Nephrology guidelines for the management of patients with ESRD treated with intensive hemodialysis. Am J Kidney Dis. 2013;62(1):187-198. Vaux et al declined to respond. Ó 2013 by the National Kidney Foundation, Inc. http://dx.doi.org/10.1053/j.ajkd.2013.09.022

Urate Oxidase Should Remain Mandatory in Patients at High Risk of Tumor Lysis Syndrome To the Editor: We read with great interest the meta-analysis by Dr LopezOlivo and colleagues.1 Although the authors adequately discuss the limitations of the studies evaluating recombinant urate oxidase (rasburicase), we believe that their conclusions should be viewed with caution. The authors themselves note that evaluating urate oxidase treatment may require additional studies. First, previous studies suggest that acute kidney injury (AKI) complicated with tumor lysis syndrome increases the likelihood of death by as much as 5-fold.2,3 These results are in accordance with several studies that suggest that AKI per se may be associated with a poor outcome.4 In patients with cancer, AKI also may decrease the chance of achieving complete remission.5 As stated by LopezOlivo et al,1 the effect of rasburicase in decreasing serum urate level, an important risk factor for AKI in these patients, is tremendous. Additionally, recombinant urate oxidase was found to be highly cost-effective in children, as well as cost-effective in adult patients 165